Method for Post-Emergence Crabgrass Control

ABSTRACT

The present invention provides a method for post-emergence selective crabgrass control by applying a composition comprising a first herbicide and a second herbicide in which the first herbicide is 2,4-dinitro-N 3 ,N 3 -dipropyl-6-(trifluoromethyl)-1,3-benzenediamine and the second herbicide is N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide to a locus where one to two leaf growth stage crabgrass is present.

This application claims the benefit of U.S. Provisional Application No.60/932,201 filed May 30, 2007.

FIELD OF THE INVENTION

This invention relates to a method for post-emergence selectivecrabgrass control in turf sites by applying a composition comprising afirst herbicide and a second herbicide in which the first herbicide is2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andthe second herbicide isN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideto a locus where crabgrass is present.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 3,764,623 discloses HerbicidalDinitro-1,3-Phenylenediamine Compounds. U.S. Pat. No. 4,818,275discloses Herbicidal Aryl Triazolinones.

The use of herbicides for crabgrass control in turf is well known. Thereare two types of herbicide applications for this purpose, pre-emergenceherbicides that prevent crabgrass seeds from germinating or emerging andpost-emergence herbicides that control emerged and actively growingplants.

Pre-emergence turf herbicides are generally more effective, but must beapplied early in the season before crabgrass seeds germinate. In orderto provide season-long control most pre-emergent herbicides need to bere-applied six to eight weeks after the initial application. Apopulation of crabgrass, either over an entire site or in localizedareas of a site, cannot be confirmed so early in the season, the timeand expense of treating turf with pre-emergence applications ofherbicides may not be needed.

Post-emergence turf herbicides are used to control crabgrass aftergermination and emergence from the soil. The benefit of using apost-emergence turf herbicide for crabgrass control is that it is usedonly if and where crabgrass is present. Some of the most commonpost-emergence turf herbicides must be reapplied several times, forexample, organic arsenicals which include MSMA (monosodiummethanearsonate), and DSMA (disodium methanearsonate); and others injureor turn turf grasses yellow after application, for example, fenoxaprop((+/−)-ethyl 2-[4[(6-chloro-2-benzoxaolyl)oxy]phenoxy}propanoate) andquinclorac(3,7-dichloro-8-quinolinecarboxylic acid).

It would be most beneficial to provide a post-emergence turf herbicidethat controlled crabgrass in one application and without injury to turfgrasses.

SUMMARY OF THE INVENTION

In accordance with the present invention, it has been found that anherbicidal composition comprising a first herbicide and a secondherbicide in which the first herbicide is2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andthe second herbicide isN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide,wherein the first herbicide and the second herbicide are present in anherbicidal effective amount, has unexpected post-emergence control ofcrabgrass.

DETAILED DESCRIPTION OF THE INVENTION

It has been unexpectedly found that an herbicidal composition comprisinga first herbicide and a second herbicide in which the first herbicide is2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andthe second herbicide isN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamidehas advantageous properties in controlling post-emergent crabgrass(Digitaria sp.) better than either component alone.

In particular, the present invention is directed to a method forpost-emergence crabgrass control by applying a composition comprising afirst herbicide and a second herbicide in which the first herbicide is2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andthe second herbicide isN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideto a locus where one to two leaf growth stage crabgrass is present.

The structural formula of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine is asfollows:

This material, commonly known as prodiamine, is a pre-emergence turfherbicide which can control crabgrass when applied prior to germinationand is not effective for post-emergent control.

The structural formula forN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideis as follows:

This material, commonly known as sulfentrazone, is a post-emergence turfherbicide which does not control crabgrass.

The terms “weed” and “weeds” refer to any unwanted vegetation in turfsites. The terms “turf”, “turf site” and “turf sites” refers to, but isnot limited to, residential and institutional lawns, athletic fields,commercial sod farms and golf course fairways and roughs. The term“ambient temperature” as utilized herein shall generally mean anysuitable temperature found in a laboratory or other working quarter, andis generally not below about 15° C. nor above about 30° C. Forcrabgrass, the one leaf growth stage is herein defined as when acrabgrass leaf first emerges through the soil and is visible. The twoleaf growth stage is herein defined as when a crabgrass plant has twovisible leaves and a third leaf is not yet visible.

The ratio of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine toN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamidevaries over a wide range but is usually in the range 10:1 to 1:1,preferably 7:1 to 2:1.

A particular embodiment of the present invention is a method forcontrolling crabgrass in turf sites which comprises applying acomposition of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide,either together or sequentially, to a locus where crabgrass is present.The herbicidal composition of the present invention is particularlyuseful in controlling crabgrass in turf sites when applied to thecrabgrass plant at the one to two leaf growth stage.

Other herbicides can be employed in conjunction with the first andsecond herbicides described above providing they do not adversely affectthe interaction between the components of this invention. For example itcan sometimes be useful to include additional herbicides to extend therange of activity in order to control a wider spectrum of weeds inaddition to crabgrass.

The herbicidal compositions of use in the present invention may beemployed in many forms and are often most conveniently prepared inaqueous form immediately prior to use. One method of preparing such acomposition is referred to as “tank mixing” in which the first andsecond herbicides in their commercially available forms, either with orwithout other additives, are mixed together by the user in a quantity ofwater.

In addition to tank mixing immediately prior to use, the compositionscontaining2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamidemay be formulated into a more concentrated primary composition which isdiluted with water or other diluent before use. Such compositions maycomprise a surface active agent in addition to the active ingredientsand examples of such compositions are set forth below.

The herbicidal compounds of use in the present invention can beformulated as a granule of relatively large particle size (for example,8/16 or 4/8 US Mesh), on fertilizer granules, as water-soluble orwater-dispersible granules, as powdery dusts, as wettable powders, asemulsifiable concentrates, as aqueous emulsions, as solutions, or as anyof the other known types of agriculturally-useful formulations,depending on the desired mode of application to the areas in whichsuppression of vegetation is desired. These formulations may contain aslittle as 0.1%, 0.2% or 0.5% to as much as 95% or more by weight of thetotal of the two herbicides.

The herbicidal compounds of use in the present invention can be in theform of a dispersible solution which comprises the herbicides dissolvedin a water-miscible solvent with the addition of a dispersing agent.

Alternatively, the composition can be in the form of water-soluble orwater-dispersible granules that disperse readily in water or otherdispersant. Water-soluble or water-dispersible granules normally areprepared to contain about 5-80% of the herbicides, depending on theabsorbency of the carrier, and usually also contain a wetting,dispersing or emulsifying agent to facilitate dispersion and may containa preservative. Typical carriers for water-soluble or water-dispersiblegranules include Fuller's earth, natural clays, silicas, and otherhighly absorbent, readily wet inorganic diluents. For example, a usefulwater-soluble or water-dispersible granule formulation contains 26.71parts of the herbicidal compounds, 30.90 parts of ammonium sulfate,30.89 parts of continental clay, 10.00 parts of sodium lignosulfonate asa dispersant, 1.00 part of sodium dioctylsuccinate as a wetting agentand 0.50 part of citric acid as a preservative. The mixture is milled,diluted with water to form a paste and the paste is extruded and driedto produce granules.

Other alternatives that may be employed are dusts which are free flowingadmixtures of the herbicides with finely divided solids such as talc,natural clays, kieselguhr, flours such as walnut shell and cottonseedflours, and other organic and inorganic solids which act as dispersantsand carriers for the herbicides. These finely divided solids have anaverage particle size of less than about 50 microns. A typical dustformulation useful herein is one containing 1.0 part or less of theherbicidal compounds and 99.0 parts of talc.

Also useful formulations for the herbicidal compounds of use in thepresent invention are wettable powders in the form of finely dividedparticles that disperse readily in water or other dispersant. Thewettable powder is ultimately applied to the locus where crabgrasscontrol is needed either as a dry dust or as an emulsion in water orother liquid. Typical carriers for wettable powders include Fuller'searth, kaolin clays, silicas, and other highly absorbent, readily wetinorganic diluents. Wettable powders are prepared to contain about 5-80%of the herbicides, depending on the absorbency of the carrier, andusually also contain a small amount of a wetting, dispersing oremulsifying agent to facilitate dispersion. For example, a usefulwettable powder formulation contains 80.0 parts of the herbicidalcompounds, 17.9 parts of Palmetto clay, and 1.0 part of sodiumlignosulfonate and 0.3 part of sulfonated aliphatic polyester as wettingagents. Additional wetting agents and/or oils will frequently be addedto a tank mix to facilitate dispersion on the foliage of the plant.

Other useful formulations for the herbicidal compounds of use in thepresent invention are emulsifiable concentrates (ECs) which arehomogeneous liquid compositions dispersible in water or otherdispersant, and may consist entirely of the herbicidal compounds and aliquid or solid emulsifying agent, or may also contain a liquid carrier,such as xylene, heavy aromatic naphthas, isophorone, or othernon-volatile organic solvents. For herbicidal application theseconcentrates are dispersed in water or other liquid carriers and appliedas a spray to the area to be treated. The percentage by weight of theherbicidal compounds may vary according to the manner in which thecomposition is to be applied, but in general comprises 0.5 to 95% of theherbicidal compounds by weight of the total composition.

Flowable formulations may also be employed. These are similar to ECs,except that the herbicidal compounds are suspended in a liquid carrier,generally water. Flowables, like ECs, may include a small amount of asurfactant, and will typically contain the herbicidal compounds in therange of 0.5 to 95%, frequently from 10 to 50%, by weight of the totalcomposition. For herbicidal application, flowables may be diluted inwater or other liquid vehicle, and are normally applied as a spray tothe area to be treated.

Other useful formulations include suspensions of the herbicidalcompounds in a relatively non-volatile solvent such as water, corn oil,kerosene, propylene glycol, or other suitable solvents.

Still other useful formulations for these herbicidal compositionsinclude simple solutions of the herbicides in a solvent in which it iscompletely soluble at the desired concentration, such as acetone,alkylated naphthalenes, xylene, or other organic solvents. Granularformulations, wherein the herbicides are carried on relative coarseparticles, for example, solid fertilizer particles, are of particularutility for aerial distribution, for penetration of cover canopy or forapplication using a spreader. Pressurized sprays, typically aerosolswherein the herbicides are dispersed in finely divided form as a resultof vaporization of a low-boiling dispersant solvent carrier may also beused.

In some circumstances it may be desirable to combine two types offormulations—e.g., one of the herbicidal compounds is used as anemulsifiable concentrate and the other herbicidal compound is dispersedas a powder in this concentrate.

The concentrate of the first and second herbicides (when used as thesole active components) in a composition for direct application to thelocus where control is desired by conventional ground methods ispreferably within the range of 0.001 to 10% by weight of thecomposition, especially 0.005 to 5% by weight, but more concentratedcompositions containing up to 40% may be desirable.

Typical wetting, dispersing or emulsifying agents that may be used inthe compositions of the present invention include, but are not limitedto, the alkyl and alkylaryl sulfonates and sulfates and their sodiumsalts; alkylaryl polyether alcohols; sulfated higher alcohols;polyethylene oxides; sulfonated animal and vegetable oils; sulfonatedpetroleum oils; fatty acid esters of polyhydric alcohols and theethylene oxide addition products of such esters; and the additionproduct of long-chain mercaptans and ethylene oxide. Many other types ofuseful surface-active agents are available in commerce. Surface-activeagents, when used, normally comprise 1 to 15% by weight of thecomposition.

In use on turf sites, the granular formulations, emulsifiableconcentrates, flowable concentrates, aqueous emulsions, solutions, etc.,may be diluted with water to give a concentration of the activeingredient in the range of 0.01% or 0.2% to 1.5% or 2.0%.

The application rates of the compositions used in the process of thepresent invention may vary over a wide range. In general any amount thatis effective to control the one to two leaf growth stage crabgrass maybe used. Preferred results are achieved at application rates in therange of from about 0.50 to 1.125 lb per acre.

The following examples further illustrate the present invention, but, ofcourse, should not be construed as in any way limiting its scope. Theexamples include protocols for the evaluation of the compositions of thepresent invention in which a beneficial effect was observed. The testcompositions used were formulated pre-mixes or commercially availableformulations of the test compounds. The following commercially availableformulations were used: sulfentrazone, Dismiss™ Turf Herbicide from FMCCorporation; prodiamine, Barricade® 4FL Herbicide from Syngenta CropProtection, Inc.

Example 1 Preparation of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideSuspension Concentrate Formulation (SC)

To an appropriately sized mixing vessel, affixed with an overheadmechanical stirrer, was added 749.0 grams of glycerine, 21.2 grams ofxanthan gum (Kelzan® M available from Monsanto Chemicals) and 18.7 gramsof hydrated magnesium aluminum silicate (Veegum available from R.T.Vanderbuilt Co. Inc.) The mixture was allowed to stir at ambienttemperature.

Into an appropriately sized slurry tank was added 4506.0 grams ofdeionized water, 156.0 grams each of melted Tergitol™ XH and Tergitol™XD (both of which are alkyl ethylene oxide/propylene oxide copolymersavailable from Dow Chemical Co.), 280.9 grams of ethoxylated sorbitanmonooleate (Agnique SMO-20-U available from Cognis Agrosolutions), 18.7grams of an isothiazolone mixture (Legend MK preservative, availablefrom Rohm and Haas Corporation) and 12.5 grams of an antifoam agent (DowCorning AF Emulsion, available from Dow Corning Corporation). Themixture was stirred at ambient temperature for 15 minutes at which time3,584.8 grams of technical2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine (95.0%active ingredient) was added portion wise followed by 1,852.9 grams oftechnicalN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide(91.9% active ingredient), also added portion wise. The resultant slurrywas milled, in two portions, in an attritor mill until a particle sizeof less than 11 microns (90% tile) was obtained. The milled slurry wastransferred to a second appropriately sized mixing vessel, affixed withan overhead mechanical stirrer. The mill was rinsed with 1127.0 grams ofdeionized water and the rinsate was added to the second mixing vessel.The glycerin, xanthan gum and hydrated magnesium aluminum silicatemixture prepared above was added to the second mixing vessel and theresultant mixture was stirred at ambient temperature and low shear fortwo hours. The resultant SC formulation contained2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideina 2:1 ratio and a concentration of 27.28% and 13.64% of the two activeingredients respectively. This SC formulation was packaged into oneliter containers for storage.

Example 2 Post-emergent herbicidal evaluation of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideon Crabgrass

The compositions of the present invention were tested for herbicidalefficacy in the following manner:

For post-emergence testing, three disposable 3 inch square pots for eachrate of application of each herbicide solution were filled with a soil,comprised of peat moss, vermiculite, bark ash, pine bark, limestone anda wetting agent (Metro Mix® 360 artificial soil, Scotts Company,Marysville, Ohio), to which about 20 to 30 crabgrass seeds (Digitariasp.) seeds were planted. The pots were placed in a greenhouse andwatered daily, thus allowing the seeds to germinate and the foliage todevelop for 11 days, until the crabgrass was at the 1-2 leaf growthstage.

Pots designated for treatment were placed on a conveyor belt and theconveyor belt fed under a spray nozzle mounted about ten inches abovethe postemergent foliage. The spray of herbicidal solution was commencedand once stabilized; the pots were passed under the spray at a speed toreceive a coverage equivalent of 30 gallons per acre. The applicationrates are those shown in Table 1 below for the individual herbicidalsolutions and the herbicide compositions of the present invention. Thepost-emergence pots were immediately placed in the green-house and notwatered for 24 hours after treatment. Thereafter they were regularlywatered at ground level. The control of crabgrass was evaluated in eachexperimental test from 1 to 22 days after treatment (DAT). The results,shown as an average of the replications, were compared with resultsobserved in untreated control pots in the same tests. The results are inTable 1 below. All test treatments contained 0.25% (by volume) of anon-ionic surfactant.

Percent control was determined by comparing the treated plants to theuntreated control using the following rating system:

Herbicide Rating System Rating Percent Description of Main ControlCategories Weed Description 0 No Effect No weed control 10 Very poorweed control 20 Slight Effect Poor weed control 30 Poor to deficientweed control 40 Deficient weed control 50 Moderate Effect Deficient tomoderate weed control 60 Moderate weed control 70 Control somewhat lessthan satisfactory 80 Severe Satisfactory to good weed control 90 Verygood to excellent weed control 100 Complete Effect Complete weeddestruction

The results, shown as an average of the replications, were compared withresults observed in untreated control plots in the same trials. Theresults are in Table 1 below.

TABLE 1 Post-emergence Control of Crabgrass (Digitaria sp.) by theCompositions of the Present Invention Average % control* Rate ofApplication at the 1-2 Leaf Growth Stage Appln. 22 Treatment (lbAI/Acre) 1 DAT 3 DAT 7 DAT 14 DAT DAT A  0.375 10 25 10 0 0 0.25 20 20 50 0 B 0.75 0 0 0 0 0 SC ** Formulation  0.75/0.375 50 60 50 40 50 from0.50/0.25 40 60 50 40 40 Example 1 0.38/0.19 30 40 10 0 0 Untreated — 00 0 0 0 Control *average of three replications ** Rate of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide,a 2:1 ratio A =N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide,Dismiss ™ Turf Herbicide available from FMC Corporation B =2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine,Barricade ® 4FL Herbicide available from Syngenta Crop Protection, Inc.

Those of ordinary skill in the art will appreciate that variations ofthe invention may be used and that it is intended that the invention maybe practiced otherwise than as specifically described herein.Accordingly, this invention includes all modifications encompassedwithin the spirit and scope of the invention as defined by the followingclaims.

1. A method for post-emergence crabgrass control said method comprisingapplying a composition comprising a first herbicide and a secondherbicide in which the first herbicide is2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine andthe second herbicide isN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideto a locus where one to two leaf growth stage crabgrass is present. 2.The method of claim 1 wherein the ratio of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine toN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideis in the range of from 10:1 to 1:1.
 3. The method of claim 2 whereinthe ratio of2,4-dinitro-N³,N³-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine toN-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamideis in the range of from 7:1 to 2:1.
 4. The method of claim 3 wherein thethe ratio is 2:1.
 5. The method of claim 4 wherein the application rateis in the range of from 0.50 to 1.125 lb per acre.